Roll out pie crust dough and put in pie pan.
In a large bowl, combine the pumpkin, apple butter, brown sugar, cinnamon, nutmeg, and salt.
Stir in eggs and milk.
Pour into pie crust.
Bake for 50-60 minutes or until a knife inserted near the center comes out clean.
If not using streusel, take pie out of oven and let cool on wire rack.
If you plan to use the streusel, make that while the pie is baking.
For the streusel- stir together the flour and brown sugar. Cut in the butter til mixture resembles coarse crumbs. Stir in the optional pecans.
After the pie tests done, take the pie out of the oven and sprinkle with the topping.
Bake for another 15 minutes.
Remove to a rack to cool.